1. Field of the Invention
The present invention relates to an image processing system, and more particularly to an image processing system for processing video signals.
2. Description of Related Art
Video printing is already known for printing a television image. Particularly the video printing from the conventional television system with 525 scanning lines is utilized as very useful means for printing decisive moments in news or sports programs.
In recent sports events or the like, video records are the often only available records, so that the role of video printing has become more and more important. Particularly the image of high definition television (HDTV) will significantly improve the image quality of video printing, and will evidently expand the application of the video printing. For example, high definition television has a resolving power of 1920.times.1035 points and can provide a high-quality image on a print up to A4 size.
However, in case of handling the image signal of the conventional high definition television in the form a digital signal, the vertical-to-horizontal ratio of each pixel is not 1:1 (square) but each pixel has a somewhat oblong rectangular shape which, for example, corresponds to the proposed standard of BTA (Broadcasting Technology Development Association). Consequently, if such data, in which the vertical-to-horizontal ratio of each pixel is not 1:1, are supplied to a printing apparatus or the like designed to process data with square pixels, a distorted image will result because the aspect ratio of the printed image is different from that of the original image.
Also similar image distortion will be encountered when a video signal of 1:1 aspect ratio, generated in an image reading unit such as a scanner, is supplied to a BTA-standard equipment such as a digital video cassette recorder.
Furthermore, the sampling frequency of 74.25 MHz employed in the high definition signal is primarily designed for use in the broadcasting studio. Since the amount of image data becomes enormous at such a sampling frequency, the frequency is generally reduced, in the usual professional and amateur appliances, to a level that can maintain tolerable image quality. For example, a sampling frequency of 48.6 MHz is employed in a so-called MUSE system. However each pixel is not square even at such a sampling frequency, such that the above-explained aspect ratio difficulty is still encountered.